Utilizing roots, time, and erosion to terrace steep hillside

Discussion in 'Planting, growing, nurturing Plants' started by warren.cascade, Jul 17, 2008.

  1. warren.cascade

    warren.cascade Junior Member

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    I am working with a south facing hillside on the Toutle river in Washington state, Twisted Hazels Orchard( https://twistedhazelsorchard.googlepages.com/home). Their is around 5 acres that makes a 120' elevation gain at about 60-70 degree slope. Basically there's alot of land that is very steep. I'm hoping to cultivate berries, fruit, nuts and various perreniels on the hillside and put a road in down the hill.

    I'm seeing this as a low priority, but would like to start installing some earthworks that would make the terracing project easier down the road. The idea would be to plant some trees in the pattern i would like the road terraced, so that the tree roots will begin to stabilize the hillside, and make it easier to cut the path/small road later.

    To help the trees get established on the hillside and need less watering I'm planning to:
    1. Make 3' diameter bundles out of 8' long 1/2" diameter broadleaf maple poles that I will be thinning from other parts of the land
    2. Stake the bundles to the hillside
    3. dig a large impression uphill from the bundle, throwing the dirt onto the bundle to help the wood break down and become a sponge.
    4. Dig 8' swales off the side of the impression, drawing water to the impression
    5. Plant DA/NF cover crops in the impression
    6. 2 years after the impression has been prepped with cover crops, and the bundle has dissentigrated into a large water sponge i'll plant in some trees and bushes.

    Questions:
    Do you think it's worth it?
    What trees would you use that have good root systems for stabilizing hillsides?
    Do you think crab apples or other fruit trees will be benefited or hindered from the large rotting bundle of maple?

    Thanks for the input.

    peace,
    warren
     
  2. bazman

    bazman Junior Member

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    Re: Utilizing roots, time, and erosion to terrace steep hillside

    I would use clumping grasses like Vetiver grass, it's also known as land nail's this will hold earth much better in the short term than any tree or bush.

    https://www.vetiver.com

    Check out this link to inspire you, includes something like what you explained.
    https://picasaweb.google.com/VetiverNetwork

    Baz
     
  3. warren.cascade

    warren.cascade Junior Member

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    Re: Utilizing roots, time, and erosion to terrace steep hillside

    I've been afraid of using that vetiver grass, since we've had problems in the NW with non-native grasses out competing native grasses. It sounds like it could really be tenacious if it got out of hand.
    Does anyone know of people using vetiver grasses in the NW?
     
  4. bazman

    bazman Junior Member

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    Re: Utilizing roots, time, and erosion to terrace steep hillside

    Vetiver grass seeds are sterile, Vetiver grass will out perform any native grass in it's job to stabilize hill sides and it won't spread. It also makes a great mulch source right in the middle of your orchard.
     
  5. ho-hum

    ho-hum New Member

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    Re: Utilizing roots, time, and erosion to terrace steep hillside

    Baz,

    Vetiver is the ultimate non-seeding 'nail it' grass. Lemon grass also has similar virtues. What we shouldnt lose site of is that a well established erosion control vector can also be slashed, raked and make a huge second layer mulch plant.

    Warren, do a bit of a search on vetiver grass. You have recieved advice from a permie who has not suggested a 'seeding grass pest' etc.

    No one mentioned bana, sudan, para, pampas etc. You were given pretty good advice, what you now need to do is evaluate this advice as to your situation.

    cheers,
     
  6. christopher

    christopher Junior Member

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    Re: Utilizing roots, time, and erosion to terrace steep hillside

    I'm with Baz and Mike on this, vetiver is unequaled for erosion control. We are running trials on it here on very steep land, and it is forming small terraces. Having said that, this is a topical climate, and perhaps your cool climate will not be suited for vetiver.
     
  7. Bennz

    Bennz Junior Member

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    Re: Utilizing roots, time, and erosion to terrace steep hillside

    I'm no expert, but 60-70 degree slope!!! There is a very real possibility that slope like that may be too much to be viable for any cropping.

    I would certainly go with trees, because the root depth holds the hills well. Plant grass amongst them, sure. N-fixers are particularly good with clump grasses.

    I am doing something similar here, off-contour planting Acacia dealbata and Alnus acuminata into pasture. My intention is too use cattle to create the terraces, as they walk up and down the rows of N-fixing trees. I call this approach 'controlled-erosion", and expect it will work, although still in the experiment stage. The tree rows are planted slightly off-contour downwards from the gullies to the ridges, to evenly disperse rainfall.

    I am on a slightly larger scale than you at 600 acres, and any 60-70 degree slopes here will be permanently retired into native rainforest species. Your soils may suit this slope better than mine, every site has its own challenges. Keeping 60-70 degree slopes up in the air is a challenge in itself on my soils.

    Digging the swales is something you need to be very confident about, on very steep country it is possible this can make erosion worse, especially if you get a dry season with associated cracking of the soil. Ditches/swales on slopes that crack can cause floodwater to go UNDER the soil surface and create major erosion issues.

    This guy Ken at https://www.minifarms.com/ has some interesting anecdotes about sustainable organic farm systems on very steep slopes, worth reading if you have not done so already.
     
  8. Paul Cereghino

    Paul Cereghino Junior Member

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    Re: Utilizing roots, time, and erosion to terrace steep hillside

    Interesting problem.. is that 60-70 degrees (as in a difficult 4 legged scramble) or 60-70 percent (as in 60 feet rise over 100 feet distance or ~35 degrees). Steep south facing slope without irrigation can be brutal in our climate, making fruit culture marginal. What is existing hydrology and irrigation opportunity. Behavior of water will be strongly affected by soil character. NRCS serves on line soil information in GIS format: https://websoilsurvey.nrcs.usda.gov/app/ It would be good to know what you're dealing with. In short 60-70 percent is interesting, 60-70 degrees is about avoiding gullies and slope failure. Given the size of the parcel, red alder (Alnus rubra) is your cheap native nitrogen fixer (you can grab bare root seedlings from along any forested roadside in winter), black locust (Robinia pseudoacacia) grows well in our region, but is very difficult to kill should you want to and will spread by seed and root. I have just started growing goumi (Eleagnus multiflora) and it is doing well -- still watching to see about its dispersal habits. We have a range of well adapted lupine (L. polyphyllus, L. latifolia). A lot depends on the existing veg. (you may have plenty of tap rooted nitrogen fixers in the form of Scot's broom!). Bundles of rotting maple won't cause any issues, trees are resourceful at foraging for what they need. I would question the labor of bundling. Consider just staking on (or slightly off) contour and wracking wood against the stakes (Brush fence). If you are looking at a 60-70 percent slope then you might consider investing in tracked machinery for a day if you are serious about a road grade, and do some contour ripping as part of road bed construction. Even a rototiller can be managed to side cast material onto your contour wood heap. If its 60-70 degrees it just you and the goats. FAO has an interesting manual - https://www.fao.org/docrep/006/t0099e/t0099e00.HTM. Am curious to get confirmation of the angle/degrees/percent thing.
     
  9. warren.cascade

    warren.cascade Junior Member

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    Re: Utilizing roots, time, and erosion to terrace steep hillside

    O.K., so only a small portion of the hillside would probably be 60 degree ANGLEd slope, but it's largely at the crest of the hillside. The mid to lower section of the hill is more like 40-30 degree ANGLE sloping down into a marsh. These are all eyed out observations, I'm going out with a measuring tape and level next week, so i'll have more precise grade calculations soon!

    I just got back from my first week of 'immersion camp'. We had a great week of digging soil test holes, plant and animal inventorying(including a black bear), clearing trails, and building camp(composting pit toilet, root cellar, kitchen site, etc). The soil samples have verified how much the red alder and broadleaf maple are doing to build soil on the site. We took a soil test in the marsh at the bottom of the hill, on the hillside over the marsh, and about 200' up a gradual hill from the ridgeline within a red alder patch. The marsh was rich friable dark soils to the 2' we dug, probably much much deeper. The ridge was straight concrete like clay, with roots only penetrated to about 3". In the red alder patch there was 9" dark brown friable top soil, and then concrete like clay soil.

    The Red Alder is making nice nitrogen rich soil on top of hard clay and a portion of the soil is getting washed down into the marsh. The hillside doesn't have enough roots, brush fence or swale like infrastructure to hold any of the nutrient rich soil as it washes down to the marsh. There is a portion of the hillside, which doesn't have much of any vegetation on it. I'm worried for this section, since the land was clearcut 12 years ago, so the Doug Fir roots that stabilized the hill are well roted, so I'm worried this section is prone to a landslide. I'd hate to lose the hillside, or disturb the marsh area below. Got to get some erosion control measures up there this year. Vetiver grass is now high on the list of possibilities to work into a erosion controlling, soil building guild for the hillside.

    Paul,
    Thanks for the links and thoughts. You're right, placing stakes and pilling up wood behind(brush fence) will work great. There are a couple steep patches on super concrete clay I think i'll try this on first. I have plenty of red alder saplings on site, so i'll transplant those and see how they do. I don't have much lupine, but would love to get it more established next year.

    Beenz,
    Wow. I'd love to see your terracing effort. It sounds great. I think I may try the vetiver, and use goats rather then cattle to help with the terracing. The deer are already doing some terracing really.

    Thanks for the input,
    Warren Neth
     
  10. Paul Cereghino

    Paul Cereghino Junior Member

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    Re: Utilizing roots, time, and erosion to terrace steep hillside

    Is the slope facing sun-ward? 12 years with no natural recruitment with alder seed landing on the site is definitely a warning sign. Sounds like reforestation on the steep part and focus early work on the lower portion. I was wondering about some habitat species that could take bad conditions and come well from cuttings. Ocean spray (holodiscus discolor), snowberry (syphoricarpos), red-flowering currant (Ribes sanguineum) all take well from hardwood cuttings and may do well on a steep slope. Artostaphylos has a survival berry and medicinal properties to the leaves. Put the alder in late fall and cross your fingers. I would ditto the earlier comment that concentrating water in a swale must be done mindfully... particularly if your soils are impermeable once you concentrate the flow, you'll need to manage it all the way down or you could be creating a gully. Use small bare root stock and plant in native soil. You're transplants will want very little top growth to support in the first years. Good luck.
     

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